open Big_int_Z

module BISet = Set.Make( 
    struct
        let compare = compare_big_int
        type t = big_int
    end )

let ( +! ) = add_big_int
let ( %! ) = mod_big_int

let () =
    let arr = Array.make 2 zero_big_int in
    Scanf.scanf "%s %s\n" (fun n d -> arr.(0) <- big_int_of_string n; arr.(1) <- big_int_of_string d);

    let n, d = arr.(0), arr.(1) in
    let rec count_pyon pos hist count =
        let next_pos, next_hist = (pos +! d) %! n, BISet.add pos hist in
        if BISet.mem next_pos next_hist then string_of_big_int count
        else
            let next_count = count +! unit_big_int in
            count_pyon next_pos  next_hist next_count
    in
    count_pyon zero_big_int BISet.empty zero_big_int |>
    Printf.printf "%s\n"